| itr | iThink Runtime |
| itss | Microsoft InfoTech Storage System File |
| itt | IconTweaker Theme |
| itv | Nostalgia Emulator Intellivision ROM |
| itw | InTouch With Database |
| itx | FileNet ITX Form Template |
| itx | IGOR Pro Text File |
| itxib | iTunes Dump Data |
| iuc | wyUpdate Client Data |
| iuf | LandMark Incremental Update File |
| ium | infoUSA Network Meter file |
| iut | SPaCIoS Tool IUT Definition |
| ivd | Bitdefender Antivirus Incremental Database |
| ivl | ISIS Volume Output interval Data |
| ivl | ILOG JViews Map Data |
| ivm | Avaya Modular Messaging Voice Message |
| ivml | INDENICA Variability Modelling Language Data |
| ivs | Aircrack-ng Initialization Vector Data |
| ivt | Beyond 20/20 Multi-dimensional Table |
| ivw | i-Vocab World Array |
| ivwr | IntelliVIEW Offline Report Data |
| ivx | Beyond 20/20 Micro-data Extract File |
| ivy | Apache IVY Module Descriptor |
| iw | Chain Engineering Database |
| iw | IdleWild Screensaver File |
| iw2 | Information Workshop 2000 Data file |
| iwcf | Incomedia Website X5 Cell Style |
| iwl | Incomedia WebSite X5 License Data |
| iwm | AimTech IconAuthor File |
| iwnew | Autonomy Interwoven iwdeploy Server Received File |
| iwold | Autonomy Interwoven iwdeploy Server Received File |
| iwt | Sunnysoft InterWrite Skin |
| iwtmp | OpenDeploy Temporary Data |
| iwxdata | iWorx LabScribe Data |
| ix | dtSearch Desktop Index |